A cast slab manufactured by continuous casting is cut into slabs having a predetermined length by oxygen cutting. At that time, a part of slab melts owing to oxygen cutting, and adhesive matter called “scarfing slag” thereby often adheres to the upper and lower ends of the longitudinal end of the slab. Scarfing processing is sometimes performed to remove surface defects of the slab. Owing to scarf processing, icicle-like adhesive matter, called “fins” of steel melted by scarf processing is generated on the slab. If hot rolling is performed with adhesive matter such as scarfing slag and fins adhering to the longitudinal end (hereinafter also sometimes simply referred to as the end) of the slab, small scratches are generated on the surface of the steel sheet owing to the adhesive matter during rolling even if the adhesive matter is small. So, techniques to remove the above-described adhesive matter prior to hot rolling have been proposed.
For example, Japanese Unexamined Patent Application Publication No. 4-283064 discloses a technique of grinding and removing scarfing slag adhering to the lower edge of the cut surface of a slab using a whetstone. Japanese Unexamined Patent Application Publication No. 8-141714 discloses a technique of mechanically removing scarfing slag adhering to the lower part of the end face of a slab using a swinging blade.
Japanese Unexamined Patent Application Publication No. 2009-45636 discloses a technique of grinding and removing a corner part in the width direction of a slab using position coordinate data of an edge part of the slab obtained by measuring the shape of the slab, although the part that is processed is not the longitudinal end face of the slab.
In the grinding and removing using a whetstone described in Japanese Unexamined Patent Application Publication No. 4-283064, the processing capacity of a grinder that performs grinding is relatively small. Therefore, when grinding the slab end face having a large area as an object of processing, a considerable grinding time is required. In addition, new grinding burrs or the like may be generated due to grinding, and multiple grinding operations need to be performed separately to remove the new burrs or the like. Therefore, the slab end face grinding operation as a whole requires a long processing time. Thus, to match the pace of the grinding operation with the production pace of slabs in a typical continuous casting equipment, a plurality of grinders need to be disposed on the transfer line that conveys continuously cast slabs. Therefore, when applying the technique disclosed in Japanese Unexamined Patent Application Publication No. 4-283064, configuration of the transfer line is complicated, and the acquisition and maintenance costs of grinders are increased.
On the other hand, the technique of Japanese Unexamined Patent Application Publication No. 8-141714 can remove burrs remaining on the lower surface of a slab. However, burrs and fins remaining on parts other than the lower surface, that is, the central part in the thickness direction and the upper corner part of the cut surface of the slab cannot be removed. In view of the decrease in yield rate due to the cutting and removing of the corner part, it is preferable to change the size of the corner part that is cut and removed depending on the size of the burr. However, such a point is not considered in Japanese Unexamined Patent Application Publication No. 8-141714.
The technique of Japanese Unexamined Patent Application Publication No. 2009-45636 detects the shape of a slab using a laser distance meter, and detects and corrects the abnormal value of distance data using optical inspection equipment. However, as shown in FIG. 6 of Japanese Unexamined Patent Application Publication No. 2009-45636, only a method of detecting the position of an edge part of a slab substantially rectangular is shown. In Japanese Unexamined Patent Application Publication No. 2009-45636, a method of determining the end position of the base iron part of a slab to which adhesive matter is adhering and the size of the adhesive matter is not shown, and the technique of Japanese Unexamined Patent Application Publication No. 2009-45636 cannot be applied to the removal of adhesive matter on the slab end face.
It could therefore be helpful to provide a method and a removal apparatus for cutting and removing adhesive matter at the end of a cuboid metal material that can reliably remove adhesive matter such as scarfing slag remaining at the end of a cuboid metal material such as a slab or a square billet in a relatively short time while suppressing the decrease in yield rate of the metal material.